sleeper1

Hi,
I have fitted 20" rims to my gt,since doing so there is a knocking uder braking, metallic like something is loose, I have been told ots not the rim hitting the brakes, but other than that im at a loss, the only suggestion I have had is that the fronts are 30 and the rear 35. and thats causing a problem. has anyone else had a problem like this or have different aspect ratio/ front and rear with or with out problems??>>????
cheers

05 gt convertible
3800miles
windveil blue

Nuke

The tire SIZE should not have anything to do with the knocking noise you're getting. Even with ABS and TCS, the minor difference in OD should not be causing these 2 systems to actuate and, even if they did, it wouldn't be a knocking sound.

First thing I'd do is remove each wheel, check for anything pbvious that may be loose and also verify that the stud clips (see attached pic) have been removed. These clips are installed to aid assembly line activities, are not required after assembly and can cause aftermarket wheels to not sit flush against the rotor. They can also cause vibration.

Bolt everything back up to spec and see what happens.

157dB

+1
check for the clips pictured above

ybnormal

check the lugs for proper style and look at the holes where the studs go around , It sounds to me like the rims front or rear may have a little gap around the wrong choice in lugs causing the rim to woble the slightest bit. I put some lugs that were for my other set of rims on my current aftermarket rims and i was getting a sound when taking off hard or stopping. good luck finding the problem. Is your car lowered or have you installed upper or lower Control arms. another source for noise.

sleeper1

cheers guys ill investigate, The car is not lowered. The rim was not sitting flush on the front so I have 5mm spacers on there, but none in the rear.
Will check for the clips and see how it goes.

2006Boss

Would look really good lowered a lit to get rid of the fender space...nice wheels